Diesel engines comprise the vast majority of prime movers for standby power generators due to their reliability, durability, and performance under load. Diesel-powered generators are depended on for backup power systems in the most critical locations: hospitals, airports, government buildings, telecommunications facilities, and even nuclear power plants.

In standby power applications, diesel generators can start and assume full-rated load in less than 10 seconds, and they typically can go long hours or more between major overhauls. This remarkable set of credentials is unique to diesel engines, but like any mechanical device, maintenance is critical for ensuring that a diesel standby generator will start and run when needed.

Standby Diesel Generator Maintenance

Generator sets on continuous standby must be able to go from a cold start to fully operational in a matter of seconds. This can impose a severe burden on engine parts. However, regular exercising keeps engine parts lubricated, prevents oxidation of electrical contacts, uses up the fuel before it deteriorates and, in general, helps provide reliable engine starting.

Exercise your generator set at least once a month for a minimum of 30 minutes loaded to no less than one-third of the nameplate rating. Periods of no-load operation should be held to a minimum because unburned fuel tends to accumulate in the exhaust system. If connecting to the normal load is not convenient for test purposes, the best engine performance and longevity will be obtained by connecting your diesel generator to a load bank of at least one-third the nameplate rating.

Preventative Diesel Generator Maintenance

Preventive maintenance for diesel engine generators plays a critical role in maximizing reliability, minimizing repairs, and reducing long-term costs. By following a diesel generator maintenance schedule and adhering to specific manufacturer recommendations, you can be sure that your standby power system will start and run when you need it most.

Because of the durability of diesel engines, most maintenance is preventive in nature. Preventive diesel engine maintenance consists of the following operations:

• General inspection
• Lubrication service
• Cooling system service
• Fuel system service
• Servicing and testing starting batteries
• Regular engine exercise

Standby Generator Maintenance Checklist

In order for your generator to power your business when you need it to, you need to create a standby diesel generator maintenance schedule that keeps your genset in good working condition. When you purchase your standby generator, there will be maintenance guidelines from the manufacturer in your owners’ manual. This should serve as a guide for your emergency generator maintenance checklist.

Diesel generators that experience more frequent use will require more frequent servicing. If it’s essential your generator is reliable in emergency situations, you will need a strict maintenance plan. Depending on your industry, there may be government regulations that dictate your maintenance schedule.

Even if your facility does not need to regularly maintain or test its generator, you will want to perform maintenance before the time of year you’re most likely to need it. This may be hurricane season, winter months or the rainy season. Your manufacturer’s warranty is likely only valid if you regularly service your generator, giving you another reason to follow your standby generator maintenance checklist.

How to Maintain a Diesel Generator

Each time you service your generator, you should start with a visual inspection. Many problems, such as leaks, worn-out parts, and dirt, can be uncovered with a quick daily or weekly look. After looking at each piece of your standby generator, complete the tasks outlined in your maintenance checklist.

Daily or Weekly

The frequency of your regular maintenance will depend on how often you use your generator and how essential it is to have standby power. After completing a visual inspection:

• Check fluid levels: coolant, oil, and fuel
• Run the generator and remedy any alerts

Monthly

• Inspect the battery and charging system
• Check hoses and belts for wear
• Remove water and sediment from the fuel tank
• Run the generator and remedy any alerts

Every 6 Months

• Change fluids and filters: oil, coolant, air, fuel
• Check ignition and replace spark plugs
• Run the generator and remedy any alerts

Annually

• Recondition diesel fuel
• Service external components, including alternator and transfer switch
• Load test the generator and remedy any alerts

After any maintenance, clean the area around the generator, check the integrity of the generator enclosure and ensure the generator is set to “Auto” rather than “Off” so it can start automatically during a power outage.

Generator Maintenance Plan

Facilities with qualified in-house technical personnel can often perform required preventive maintenance on diesel generators. Other facility managers prefer to contract with a local service provider or power system distributor for regular maintenance service, especially if they have generators in multiple locations. For unplanned maintenance, engine repairs, or overhauls, it is always best to use qualified diesel service technicians.